Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Per Share
Net income	$ 32,115	$ 36,761	$ 34,255
Weighted average basic shares outstanding	1,836	1,855	1,853
Add: Effect of dilutive securities	5	8	5
Weighted average diluted shares outstanding	1,841	1,863	1,858
Earnings per share:
Basic	$ 17.49	$ 19.82	$ 18.49
Diluted	$ 17.44	$ 19.73	$ 18.44